The paper "Transmission Control Protocol in Wireless Networks" is an engrossing example of coursework on logic and programming. The application layer can be explained as an abstraction layer specifying the interface methods and shared protocols that are used in the communication network by communicating hosts. This abstraction is employed in both computer networking standard models, which is the OSI model (Open Systems Interconnection model) and TCP/IP (Internet Protocol Suite). Even though the two models are similar in terms of their specific highest level layer, they have different detailed definitions and functions. TCP (Transmission Control Protocol) is a protocol that is reliable and connection-oriented.
In the IP, TCP is a major protocol (Leung, K. and Li, V. 2006, 64). The origin of TCP rates back to the implementation of the initial network where it complimented the IP. Thus, the whole suite is usually known as TCP/IP. In TCP/IP, it is the application layer that contains the interface methods and communication protocols used across an IP network for process-to-process communications. The Application layer protocols contain the following protocols: File Transfer Protocol (FTP), Domain Name System (DNS), Simple Mail Transfer Protocol (SMTP), and Hypertext Transfer Protocol (HTTP).
These protocols define how clients and servers (application processes), running on distinct end systems, communicate with each other. The following figure is an example of TCP offering reliable data transfer over IP network to File transfer protocol using Ethernet. 1.2. Hypertext Transfer Protocol (HTTP) 1.2.0. Definition A Hypertext Transfer Protocol can be explained as hypermedia, distributed, collaborative information systems application protocol. In other words, HTTP is a set of rules for file transfer (multimedia, sound, text, video, and graphic images) on the World Wide Web.
Hypertext can be explained as a structured text using hyperlinks (logical links) between nodes that contain text. Hypertext is manipulated using HTML (Hypertext Markup Language). 1.2.1. Uses of HTTP It provides a data communication foundation for the WWW (World Wide Web) where it runs and depends on the TCP/IP protocol suite to function. The protocol that transfers or exchanges the hypertext is the HTTP. In the transmission of information over the internet, the primary protocol for this function is HTTP (Berners-Lee, T., Fielding, R. and Frystyk, H.
1996, 5). Clients on the internet can make requests for various kinds of content using HTML and HTTP from application servers and the World Wide Web hosting the content. 1.2.3. Function In order to identify the HTTP resources across the internet (such as web servers), URLs (Uniform Resource Locators) which are the unique identifiers used. URL can be defined as the combination of the client, filename, the page retrieval scheme, the full path, and the location of the site. The URL can also contain information like the TCP port number that will be used.
The following figure shows an example of an URL. HTTP offers various authentication schemes like digest access and basic access authentication that operate through a challenge-response mechanism whereupon identification, the server before providing the requested content issues a challenge (Franks et al, 1999, 8). Typically, the entire process of HTTP takes place in four steps namely: A request for the page required is sent by the client to the web server; The request is received and analyzed by the server which then sends an ACK back to the client together with the required HTML code for making the page; The client then starts deciphering the HTML and creating the page; Lastly, in succeeding requests, the client retrieves any objects that are embedded such as images.
After retrieval of all the page elements, the browser of the client displays the complete Web page. Apart from providing a mechanism for receiving data by the client from the server, HTTP also provides other types of communication like data passing from a client to a server. These mechanisms in the HTTP specifications are regarded as methods.
Berners-Lee, T., Fielding, R. and Frystyk, H., 1996. Hypertext transfer protocol--HTTP/1.0 (No. RFC 1945).
Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S., Leach, P., Luotonen, A. and Stewart, L., 1999. HTTP authentication: Basic and digest access authentication (No. RFC 2617).
Goerzen, J., 2004. Domain Name System. In Foundations of Python Network Programming (pp. 65-85). Apress.
Leung, K.C. and Li, V.O., 2006. Transmission control protocol (TCP) in wireless networks: issues, approaches, and challenges. IEEE Communications Surveys & Tutorials, 8(4), pp.64-79.
Matthews, J., 2005. Computer networks: Internet protocols in action. John Wiley & Sons.
Myers, J., 1996. Local mail transfer protocol (No. RFC 2033).